Testing switch



Aug. 20, 1929. H. BLAKESLEE 1,725,049

TESTING SWITCH Filed Aug. 22, 1928 1 1 1 H S 8 Q i 27 //Vl /VTOA Q) 14wam Patented Aug. 20, 1929.

UNITED STATES PATENT OFFICE.

I HENRY J. BLAKESLEE, OF MARLBORO', CONNECTICUT. I

TESTING swrrcn.

Application filed August 22, 1928. Serial No. 301,218.

This invention relates to a switch of the knife blade type which isconstructed to facilitate the connectionof testing or measuringinstruments, such a switch for instance as is adapted to be insertedbetween an electrical meter and the current supply.

The object of the invetion is to provide a simple, compact andconvenient combination of a knife blade switch and a jack whereby a plugconnected with a testing or measuring instrument may be readily thrustinto the jack and that instrument be connected in series with the switchterminals, the arrangement being such that the switch blade must beopened before the jack plug can be inserted, the plug must be withdrawnbefore the switch can be closed, and the switch must be closed beforethe cover of the switch can be closed. v

This object is attained by locating the jack with itsmembers engagedwith eachv other, between the terminals of the switch and with onemember of the jack electrically connected with one switch terminal andthe other member of the jack electrically connected with the otherswitch terminal. In normal use, with the circuit closed, the knife bladeconnects the switch terminals and carries the current as usual. When itis desired to connect a testing or measuring instrument the knife bladeis opened and the plug thrust between the jack members, which action.

places the instrument to which the jack is connected in series with theswitch terminals. As the jack members are in contact with each otheruntil the plug is inserted, opening the switch does nbt interrupt theregular service.

In the accompanying drawings Fig. 1 shows a plan of a switch constructedaccording to this invention. Fig. 2 shows a side elevation of the switchwith the base and cover in section. Fig. 3 is a side view of the switchshowing the blade opened and a plug thrust into the jack. Fig. 4 is adiagram illustrating a use of a switch that embodies this invention.

" The base 1 of the switch block is made of insulating material,desirably porcelain, of any suitable length depending upon the number ofswitches that are to be mounted thereon. A cover 2, usually of a similarinsulating material as the base, is placed over the base to enclose theswitch.

The switch blade 3 of conducting material and provided with a knob orfinger piece 4 are thrust between "the jack members so that ofinsulating material, is held by the pivot 5 between the conducting ears6 that are fastened to the base by screw 7. The swinging end of theswitch blade is adapted to pass into and out of the spaeebetween thespring fingers 8 that are fastened to the base by a screw 9.

The jack shown consists of a member that has an upturned limb 10 and alimb 11 at substantially right angles thereto, which latter limb iselectrically connected with the blade pivoting ears 6 andis fastened inposition by the screws 7 and 13. The screw 13 is provided with a wireclamp 12 and a binding nut 14. The other member of the jack has adownturned finger 15 bent from the upright limb 16 that at its lower endhas an angular extension 17-whichis electrically connected with thespring fingers 8 and is held in position by the screws 9 and 19. On thescrew 19 is a clamp 18 and a binding nut 20. The adjacent members of thejack are bent so that normally they bear against each other, and thesemembers are also slitted to permit the passage through them of the knifeblade. The plug, which has a handle 21 and a cable 22 with the requiredconductors to connect it with the testing or measuring instrument, hasconducting plates 23, 24 that are separated from each other by aninsulating strip 25.

When a testing or measuring instrument is to be connected the switchblade is opened as shown in Fig. 3, and the terminals of the plugcurrent from one switch terminal or binding nut will pass from one jackmember through the plug and instrument connected with the plug to theother jack member and other switch terminal or bindin nut.

' The arrangement deseri%ed is very compact and parts'are simple to makeand assemble.

.The switch blade can be instantly opened and a jack plug inserted forthe purpose of connecting a measuring or testing instrument in the pathof the circuit normallycompleted by the switch blade. In Fig. 4 a meter26. with a series of controlling switches is illustrated, one of whichswitches is indicated as connected with a measuring instrument 27, suchas a rotary standard. When the switch is opened and the plug is insertedin the jack in such an arrangement, the circuit which includes one ofthe current carrying coil: 28 of the meter is through the standard.

7 connect and disconnect the circuit terminals,

and a jack with one member electrically connected with one terminal andanother member electrically connected with the other terminal.

2. A switch block comprising a base having members which are slitted topermit the movecircuit terminals, a conducting blade pivot ally attachedto the base and adapted to open,

and close the circuit between said terminals, and a jack with one memberelectrically connected with one terminal and another member electricallyconnected with the other terminal.

3. A switch block comprising a base having circuit terminals, earsattached to the base and electrically connected with one circuitterminal, spring fingers attached to the base and electrically connectedwith the other circuit terminal, a blade pivotedbetween aid ears andadapted to swin into and ou of contact with said spring ngers, and ajack with one member electrically connected with said ears and anothermember electrically connected with said spring fingers;

a. A switch block comprising a base having circuit terminals, a switchblade adapted to connect and disconnect the circuit terminals, and ajack interposed between the circuit terminals with one memberelectrically connected with one terminal and another member electricallyconnected with the other terminal, said jack members being'slitted topor mit the connection and disconnection of the electrically connectedwith said ears and fingers, said jack having yieldingly engaged ment ofsaid blade.

6. A switch block'comprising a base, switch 'to connect and disconnectthe switch terminals, a conducting spring finger electrically connectedwith one switch terminal and circuit terminal, and a conducting springfinger connected with the other switch terminal and circuit terminal,said fingers being normally engaged but adapted to' se arate and receivea jack plug when the-switc is open. 7

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